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Homework Help: Resistors in Series

  1. Apr 7, 2013 #1
    1. The problem statement, all variables and given/known data

    Three silver wires of equal length are connected in series with a 1.50 V battery. Their cross-sectional areas are 1.00, 5.00 and 10.0 cm2. (a) What is the potential difference across the narrowest wire? (b) The medium wire? (c) The widest wire?

    2. Relevant equations
    V= IR

    1/Req = 1/R1 + 1/R2 + 1/R3 + … + 1/Rn

    3. The attempt at a solution
    Since the cross sectional area increases for each wire in the series, it can be assumed that the resistivity decreases from left to right or right to left (depending on how you draw your diagram).
    That is:
    R1 < R2 < R3.

    I know the length of each wire is the same. However, I do not know the current. All the question provides me is the cross-sectional area of each wire.

    Any help would be appreciated. (Also I will return the favor if I can. That depends on whether or not I have studied the problem you need assistance with.)

    Thank you!
  2. jcsd
  3. Apr 7, 2013 #2
    Your relevant equation is for parallel resistors.
  4. Apr 7, 2013 #3


    User Avatar

    Staff: Mentor

    Hi franky1994, Welcome to Physics Forums.

    While current, lengths, and resistivity of the metal are not supplied, you should be able to compare the resistances of the segments. Consider how the resistance of a wire varies with respect to length and cross sectional area. Hint: What happens if you arbitrarily assign a resistance of 1Ω to the first wire segment? What would the other resistances be?
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